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- Posts: 104
- Joined: Tue Aug 04, 2015 9:57 pm
We are in the process of validating a method for inositol within a powdered nutrient blend. The method is based on the USP Monograph for Inositol utilizing a Ca++ Ion exclusion column - unfortunately we have a coeluter that does not look like it will resolve appropriately with allowed levels of modification of the method parameters outlined in the monograph.
My question is not regarding finding a way to resolve these two - I am pretty sure I could figure that out, but probably not without major modifications to the method (changing column type, mobile phase, detector etc), and we actually have a GCMS method that solves this problem. However switching instruments or substantial swaying from the monograph will cause issues with our in house auditor and if that can be avoided I would like to do so.
My question is with regard to dealing with the co-eluter in our calculations. Our preliminary and possibly inappropriate way to do so is to run an inositol free matrix blank and do a manual area subtraction of the coeluter peak from our analyte peaks.
At this point we have all the data and I am going to proceed with my protocol and report, if at least for the opportunity to practice and learn from the process even if it means getting laughed at and kicked in the ass, but would appreciate comments on whether or not others have proceeded in such a fashion with regard to an unresolvable co-eluter (utilizing a mandated method) and just explained the situation and process for dealing with it in their validation protocol and report.
Thanks